(CNN) -- Applications for health insurance coverage under President Barack Obama's sweeping healthcare law will go from 21 pages to three, according to a White House official, who said the change was part of an effort to simplify the implementation of Obamacare.

"The President wants the Administration to be as flexible and nimble as possible in implementing the ACA law," the White House official said, referring to the law's official name, the Affordable Care Act. "It is a complex undertaking, and it is particularly important to the success of the law that enrollment into the Markteplaces be as user friendly as possible."

Starting this fall, the some 15 million Americans who buy health insurance on the individual market will be able to shop for and enroll in health insurance through state-based exchanges, with coverage taking effect in January. By 2016, some 24 million people will get insurance through the exchanges, while another 12 million will continue to get individual coverage outside of them, the Congressional Budget Office estimates.

A draft application to receive insurance on the exchanges topped out at 21 pages, the White House official said, which prompted criticism that it was overly complicated.

"Obviously, the drafting of the Marketplace application is just one small piece of ACA implementation," the official continued. "But we hope that people concerned with implementation will view this corrective action as a positive step and a demonstration of our interest in taking whatever actions we can to make the law work well for all."

The Affordable Care Act was passed in 2010 with loud opposition from Republicans, who have repeatedly tried to repeal the measure in Congress. The centerpiece of the law, an individual requirement to obtain health care insurance, was upheld as constitutional by the Supreme Court in 2012.